Control valve for variable displacement compressor

ABSTRACT

A control valve according to one embodiment includes a shaft that transmits the solenoidal force to a valve element. The control valve also provides for stable operation of a variable displacement compressor even under high-temperature and high-pressure environments. A solenoid includes a bottomed sleeve into which the pressure of refrigerant is introduced, a core secured coaxially to the sleeve, a plunger, contained in the sleeve on its bottom side, which is displaceable integrally with the shaft in a direction of axis line, a first spring that applies the biasing force in a valve opening direction to the shaft, a second spring that applies the biasing force in a valve closing direction to the plunger, and a shaft support member, which is press-fitted such that the shaft support member is secured to an inner wall of the sleeve near its bottom portion. The second spring is set between the shaft support member and the plunger.

CLAIM OF PRIORITY

This application is a Divisional of U.S. patent application Ser. No.14/624,966, filed on Feb. 18, 2015, and entitled, “Control Valve forVariable Displacement Compressor”, which further claims priority toJapanese Patent Application No. 2014-036184, filed Feb. 27, 2014, andare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control valve for controlling thedischarging capacity of a variable displacement compressor.

2. Description of the Related Art

An automotive air conditioner is generally configured by arranging andplacing a compressor, a condenser, an expander, an evaporator, and soforth in a refrigeration cycle. The compressor is, for example, avariable displacement compressor (hereinafter referred to simply as“compressor” also) capable of varying the refrigerant dischargingcapacity in order to maintain a constant level of cooling capacityirrespective of the engine speed. In this compressor, a piston forcompression is linked to a wobble plate, which is mounted to arotational shaft rotatingly driven by an engine. And the refrigerantdischarging rate is regulated by changing the stroke of the pistonthrough changes in the angle of the wobble plate. The angle of thewobble plate is changed continuously by changing the balance of pressureworking on both faces of the piston as part of the dischargedrefrigerant is introduced into a hermetically-closed crankcase. Thepressure within this crankcase (hereinafter referred to as “crankpressure”) Pc is controlled by a control valve for a variabledisplacement compressor (hereinafter referred to simply as “controlvalve” also), which is provided between the discharge chamber and thecrankcase of the compressor.

Such a control valve is often configured as an electromagnetic valve andhas a valve hole, through which to communicate between the dischargechamber and the crankcase, within a body. And the opening degree of avalve section is regulated by moving a valve element, placed within thebody, toward and away from the valve hole, thereby controlling the flowrate of refrigerant introduced into the crankcase. The valve openingdegree is regulated by a balance among a force, generated by arefrigerant pressure, acting on the valve element, a drive forcegenerated by a solenoid, and a biasing force of a spring placed for thepurpose of regulating a control setting value.

RELATED ART LIST

(1) Japanese Unexamined Patent Application Publication No. 2005-214059.

In recent years, spurred by the global warming issue, it is beingproposed that alternative chlorofluorocarbon (CFC), which isconventionally used as the refrigerant used in the refrigeration cyclebe replaced by carbon dioxide and the like. However, in therefrigeration cycle where, for example, carbon dioxide is used, thepressure of refrigerant is increased to a supercritical range exceedingthe critical temperature thereof and therefore the discharge pressure ofrefrigerant gets very high. As a result, required is a control valvewhere a stable operation of the compressor can be ensured even undersuch high-temperature and high-pressure environments.

SUMMARY OF THE INVENTION

A purpose of the present invention is to provide a control valve forensuring a stable operation of a variable displacement compressor evenunder high-temperature and high-pressure environments.

One embodiment of the preset invention relates to a control valve for avariable displacement compressor that varies a discharging capacity ofthe compressor for compressing refrigerant led into a suction chamberand discharges the compressed refrigerant from a discharge chamber, byregulating a flow rate of the refrigerant led into a crankcase from thedischarge chamber. The control valve includes: a body having a dischargechamber communication port communicating with the discharge chamber, acrankcase communication port communicating with the crankcase, a valvehole formed in a passage connecting the discharge chamber communicationport and the crankcase communication port, and a valve chamber formedbetween the valve hole and the crankcase communication port; a valveelement for opening and closing a valve section by moving toward andaway from the valve hole, the valve element being arranged in the valvechamber; a solenoid, provided on the body, which generates a solenoidalforce with which to drive the valve element in a valve closing directionin accordance with an amount of current supplied thereto; and a bleedhole that enables the refrigerant to be leaked from the dischargechamber communication port to the valve chamber while the valve sectionis being closed, the bleed hole having a leak passage, whose diameter issmaller than that of the valve hole, and the bleed hole being providedradially outward of the valve hole in the body.

A raised portion, which is of a stepped shape, is provided on an endsurface of the body at a discharge chamber communication port side, andthe leak passage is open on the discharge chamber communication portside in the raised portion.

By employing this embodiment, a minimum required refrigerant can bedelivered through the bleed hole even while the valve section is beingclosed, so that the circulation of oil in the compressor can be ensured.In particular, the diameter of the leak passage, which forms an inlet ofthe bleed hole, is made small, and the inlet thereof is opened on anupper surface of the stepped shape thereof; this can prevent or suppressa foreign material from entering into the bleed hole. If the foreignmaterial should enter the discharge chamber communication port and hitthe raised portion, it is highly probable the foreign material will falloff of the raised portion and will therefore be less likely to enter theleak passage. Hence, the circulation of oil can be ensured. As a result,the stable operation of the variable displacement compressor can beensured even under high-temperature and high-pressure environments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system chart showing a refrigeration cycle of an automotiveair conditioner according to an embodiment;

FIG. 2 is a cross-sectional view showing a structure of a control valveaccording to an embodiment;

FIG. 3 is a partially enlarged cross-sectional view of the upper half ofFIG. 2;

FIG. 4A and FIG. 4B are each a partially enlarged view of a controlvalve;

FIG. 5A and FIG. 5B are each a partially enlarged view of a controlvalve; and

FIG. 6 is a graph showing a control characteristic of a solenoid.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described by reference to the preferredembodiments. This does not intend to limit the scope of the presentinvention, but to exemplify the invention.

Embodiments of the present invention will now be described in detailwith reference to the accompanying drawings. In the followingdescription, for convenience of description, the positional relationshipin each structure may be expressed as “vertical” or “up-down” withreference to how each structure is depicted in Figures.

FIG. 1 is a system chart showing a refrigeration cycle of an automotiveair conditioner according to an embodiment. The air conditioneraccording to the present embodiment includes a so-called supercriticalrefrigeration cycle that uses carbon dioxide, which operates under ahigh pressure, as the refrigerant. This air conditioner includes avariable displacement compressor (hereinafter referred to simply as“compressor” also) 101, a gas cooler 102, an expander 103, an evaporator104, and a receiver 105. Here, the compressor 101 compresses a gaseousrefrigerant circulating through the refrigeration cycle. The gas cooler102 functions as an external heat exchanger that cools a compressedhigh-pressure gaseous refrigerant. The expander 103 adiabaticallyexpands the cooled refrigerant so as to reduce the pressure thereof. Theevaporator 104 evaporates the expanded refrigerant and removes theevaporative latent heat so as to cool air inside a vehicle'scompartment. The receiver 105 separates the evaporated refrigerant intogas refrigerant and liquid refrigerant and then returns the thusseparated gaseous carbon dioxide to the compressor 101.

The compressor 101 has a not-shown rotational shaft, which is freelyrotatably supported within crankcase 116. A wobble plate is tiltablyprovided in this rotational shaft. And an end of the rotational shaftextends outside the crankcase 116 and is connected to an output shaft ofan engine by way of a pulley. A plurality of cylinders 112 are arrangedaround the rotational shaft, and a piston, which performs areciprocating motion by the rotational motion of the wobble plate, isprovided in each cylinder 112. Each cylinder 112 is connected to asuction chamber 110 through a suction valve and is connected to adischarge chamber 114 through a discharge valve. The compressor 101compresses the refrigerant, which has been led into the cylinders 112through the suction chamber 110, and discharges the compressedrefrigerant through the discharge chamber 114.

The angle of the wobble plate of the compressor 101 is kept in aposition where, for example, the load of a spring biasing the wobbleplate in the crankcase 116 and the load caused by the pressures workingon both faces of the piston connected to the wobble plate are balanced.This angle of the wobble plate can be changed continuously as follows.That is, a crank pressure Pc is changed as part of the dischargedrefrigerant is introduced into the crankcase 116, and the balance ofpressures working on the both faces of the piston is changed, therebychanging continuously the angle thereof. Changing the stroke of thepiston by varying the angle of the wobble plate regulates thedischarging capacity of refrigerant. The crank pressure Pc is controlledby a control valve 1, which is provided between the discharge chamber114 and the crankcase 116 of the compressor 101.

In other words, a part of the discharged refrigerant of the compressor101 is led into the crankcase 116 by way of the control valve 1 and isused to control the capacity of the compressor 101. The control valve 1is configured as a solenoid-driven electromagnetic valve, and theelectric conduction state and/or amount is controlled by a control unit120. In the present embodiment, the control unit 120 outputs a pulsesignal, which has been set to a predetermined duty ratio, to a drivecircuit 122. Then the control unit 120 has the drive circuit 122 outputa current pulse associated with the duty ratio. In this manner, thesolenoid is driven. The control valve 1 regulates the flow rate ofrefrigerant delivered from the discharge chamber 114 to the crankcase116 such that a differential pressure (Pd−Ps) between a dischargepressure Pd and a suction pressure Ps of the compressor 101 can bebrought closer to a preset differential pressure, which is a controltarget value. Thereby, the discharging capacity of the compressor 101varies. That is, the control valve 1 functions as a so-called (Pd−Ps)differential pressure regulating valve.

An orifice 119 is provided in a refrigerant passage 118 through whichthe crankcase 116 and the suction chamber 110 communicate. Therefrigerant inside the crankcase 116 is leaked to a suction chamber 110side through the orifice 119, so that the crank pressure Pc will not beexcessively high. A check valve 130 is provided in a refrigerant passageprovided between the discharge chamber 114 and a refrigerant outlet inthe compressor 101.

The control unit 120 includes a CPU for performing various arithmeticprocessing's, a ROM for storing various control programs, a RAM used asa work area for data storage and program execution, an I/O interface,and so forth. The control unit 120 has a PWM output unit for outputtinga pulse signal having a specified duty ratio. However, such a PWM outputunit may be configured using a known art and therefore the detaileddescription thereof is omitted here. The control unit 120 determines theaforementioned preset differential pressure, based on predeterminedexternal information detected by various sensors (e.g., the enginespeed, the temperatures inside and outside the passenger compartment,and the air-blowout temperature of the evaporator 104). Also, thecontrol unit 120 controls the electric conduction state of and/or amountto the control valve 1 in order to obtain a solenoidal force required tomaintain the preset differential pressure. Suppose now that there is arequest for cutting down on the acceleration for the purpose of reducingthe load torque of the compressor 101 during a high load state (e.g.,while a vehicle is accelerating or running uphill). Then, the controlunit 120 turns off the solenoid or suppresses the electric conductionamount to a predetermined lower limit, and thereby switches the variabledisplacement compressor to an operation mode where the compressoroperates with the minimum capacity.

The expander 103, which is configured as a so-calledthermostatic-expansion valve, regulates a valve opening degree byfeeding back the temperature of refrigerant at an outlet side of theevaporator 104 and then supplies a liquid refrigerant, which meets athermal load, to the evaporator 104. The refrigerant, which has passedthrough the evaporator 104, is returned to the compressor 101 via thereceiver 105 and is again compressed.

The check valve 130 maintains its opened state as long as thedischarging capacity of the compressor 101 is large to a certain degreeand a differential pressure (Pd−Pd1) between the discharge pressure Pdof the discharge chamber 114 and an outlet pressure Pd1 at therefrigerant outlet exceeds a valve opening differential pressure. Thisvalve opening differential pressure is set by the load of a built-inspring of the check valve 130. If, in contrast thereto, the dischargingcapacity of the compressor 101 is small and the discharge pressure Pddoes not sufficiently get high (e.g., during a minimum capacityoperation), the check valve 130 will be closed due to the biasing forceof the spring and thereby the back-flow of refrigerant from a gas cooler102 side to the discharge chamber 114 will be prevented. Note that thecheck valve 130 is closed while the compressor 101 is operating with theminimum capacity. However, the refrigerant discharged from the dischargechamber 114 is returned to the suction chamber 110 via the control valve1 and the crankcase 116. Thus, the internal circulation of refrigerantgas within the compressor 101 is assured.

FIG. 2 is a cross-sectional view showing a structure of the controlvalve 1 according to an embodiment. The control valve 1 is constitutedby integrally assembling a valve unit 2 and a solenoid 3. The valve unit2 has a body 5 of stepped cylindrical shape. Though the body 5 is formedof brass in the present embodiment, it may be formed of an aluminumalloy. The body 5 has ports 10, 12, and 14 in this order from top down.Of these ports, the port 10 is provided in an upper end of the body 5,and the ports 12 and 14 are each provided on a lateral side thereof. Theport 10 functions as a “discharge chamber communication port” thatcommunicates with the discharge chamber 114. The port 12 functions as a“crankcase communication port” that communicates with the crankcase 116.The port 14 functions as a “suction chamber communication port” thatcommunicates with the suction chamber 110.

In the body 5, a valve seat forming member 16 of stepped cylindricalshape is provided in a passage that communicates between the port 10 andthe port 12. The valve seat forming member 16 is formed by quenching astainless steel (e.g., SUS420), and the hardness thereof is higher thanthat of the body 5. The valve seat forming member 16 is coaxiallyinserted to an upper portion of the body 5 and is secured such that theupper portion of the body 5 is swaged inward. The valve seat formingmember 16 has a through-hole along an axis line, and a lower half of thethrough-hole forms a valve hole 18. A valve chamber 20, whichcommunicates with the port 12, is formed below the valve seat formingmember 16. The lower half of the valve seat forming member 16 is oftapered shape such that the outside diameter thereof is graduallyreduced from an upper part to a lower part of the lower half thereof,and the lower half thereof extends into the valve chamber 20. A valveseat 22 is formed on a lower end surface of the valve seat formingmember 16. A valve element 24 is provided in the valve chamber 20 insuch a manner as to face the valve seat 22 from below. The openingdegree of a valve section is regulated by moving the valve element 24toward and away from the valve seat 22.

A partition wall 26 is so provided that an internal space of the body 5is divided into an upper space and a lower space. The valve chamber 20is formed on an upper side of the partition wall 26, and a workingchamber 28 is formed on a lower side thereof. The valve chamber 20communicates with the crankcase 116 through the port 12. The workingchamber 28 communicates with the suction chamber 110 through the port14. A guide portion 30, which extends in a direction of axis line, isprovided in a center of the partition wall 26. A guiding passage 32 isso formed as to run through the guide portion 30 along the axis line,and an elongated actuating rod 34 is slidably inserted to the guidingpassage 32 in the direction of axis line. The valve element 24 isprovided coaxially on an upper end of the actuating rod 34. The valveelement 24 and the actuating rod 34 are formed integrally with eachother by performing a cutting work on a stainless steel.

The guide portion 30 protrudes as a small bump on an upper surface sideof the partition wall 26 and protrudes as a large protrusion on a lowersurface side thereof. The guide portion 30 is of tapered shape such thatthe outside diameter thereof is gradually reduced from an upper part toa lower part thereof, and the guide portion 30 extends into the workingchamber 28. With this configuration and arrangement, a sufficient lengthof the guiding passage 32 is ensured and the actuating rod 34 is stablysupported. The valve element 24 and the actuating rod 34 operate andmove integrally together with each other, and the valve element 24closes and opens the valve section by touching and leaving the valveseat 22, respectively, on the upper end surface of the valve element 24.The hardness of the valve seat forming member 16 is sufficiently high.Thus, the valve seat 22 is hardly deformed by repeated seating of thevalve element 24 on the valve seat 22, thereby ensuring the durabilityof the valve section.

A retaining ring 36 (E-ring) is fitted to a lower part of the actuatingrod 34, and a discoidal spring support 38 is provided such that themovement of the lower part of thereof in a downward direction isrestricted. A spring 40, which biases the actuating rod 34 downward (ina valve closing direction) (functioning as a “first biasing member”), isset between the spring support 38 and the partition wall 26. The spring40 is a tapered spring where the diameter thereof is reduced startingfrom the lower surface of the partition wall 26 toward the springsupport 38 located therebelow. Having the guide portion 30 formed in atapered shape as described above allows the tapered-shape spring 40 tobe arranged as described above. A lower part of the body 5 is asmall-diameter part 42 and constitutes a coupling portion with thesolenoid 3.

A strainer 44, which suppresses foreign materials from entering the port10, is fitted in an upper end opening of the body 5. Since the foreignmaterial, such as metallic powders, may possibly be contained in therefrigerant discharged from the compressor 101, the strainer 44 preventsor suppresses the foreign material from entering the interior of thecontrol valve 1. The strainer 44 has a bottomed cylindrical filter 46and is configured such that an opening end of the filter 46 isreinforced by a ring-shaped metallic plate 48. The filter 46 is formedusing a metal mesh. The strainer 44 is secured such that the metallicplate 48 is press-fitted to the body 5 while the bottom of the strainer44 faces upward. As shown in FIG. 2, the strainer 44 is mounted insidethe body 5, so that any deformation thereof caused by physical contactwith an external structure is prevented.

The solenoid 3 includes a cylindrical core 50, a bottomed cylindricalsleeve 52 inserted around the core 50, a plunger 54, which is containedin the sleeve 52 and which is disposed opposite to the core 50 in thedirection of axis line, a cylindrical bobbin 56 inserted around thesleeve 52, an electromagnetic coil 58 wound around the bobbin 56, acylindrical casing 60, which is so provided as to cover theelectromagnetic coil 58 from outside, a connecting member 62 of steppedcylindrical shape, which is assembled, between the core 50 and thecasing 60, in a position above the bobbin 56, and an end member 64,which is so provided as to seal off a lower end opening of the casing60.

The sleeve 52, which is formed of a non-magnetic material, houses theplunger 54 in a lower half thereof. A circular collar 66 is embedded inthe end member 64. The collar 66 is set, between the sleeve 52 and thecasing 60, in a position below the bobbin 56. The casing 60, theconnecting member 62 and the collar 66, which are each formed of amagnetic material, form a yoke of the solenoid 3. The valve unit 2 andthe solenoid 3 are secured such that the small-diameter part 42 (lowerpart) of the body 5 is press-fitted to an upper end opening of theconnecting member 62. It is to be noted here that, in the presentembodiment, the body 5, the valve seat forming member 16, the connectingmember 62, the casing 60 and the end member 64 form a body for the wholecontrol valve 1.

An insertion hole 67 is so formed as to run through the core 50 in acenter thereof in the direction of axis line. And a shaft 68 is insertedinto the insertion hole 67 in such a manner as to penetrate along theinsertion hole 67. The shaft 68 is formed coaxially with the actuatingrod 34 and supports the actuating rod 34 from below. The diameter of theshaft 68 is larger than that of the actuating rod 34. The plunger 54 isassembled to a lower half of the shaft 68. In the present embodiment,the shaft 68 and the actuating rod 34 constitute a “transmitting rod”that transmits the solenoidal force to the valve element 24.

The plunger 54 is coaxially supported by the shaft 68 in an upperportion of the plunger 54. A retaining ring 70 (E-ring) is fitted to apredetermined position in an intermediate part of the shaft 68 in thedirection of axis line, and the retaining ring 70 works to restrict themovement of the plunger 54 in an upward direction. A plurality ofcommunicating grooves 71 formed in parallel with the axis line areprovided on a lateral surface of the plunger 54. The plurality ofcommunicating grooves 71 form communicating paths through which therefrigerant is made to pass between the plunger 54 and sleeve 52.

A ring-shaped shaft support member 72 is press-fitted in an upper end ofthe core 50, and an upper end of the shaft 68 is slidably supported bythe shaft support member 72 in the direction of axis line. An outerperiphery of the shaft support member 72 is partially notched andthereby a communicating path is formed between the core 50 and the shaftsupport member 72. Through this communicating path, the suction pressurePs of the working chamber 28 is led into the interior of the solenoid 3,too.

The diameter of a lower end of the sleeve 52 is slightly reduced, and aring-shaped shaft support member 76 (functioning as a “supportingmember”) is press-fitted to a reduced diameter portion 74 of the sleeve52. The shaft support member 76 slidably supports a lower end part ofthe shaft 68. In other words, the shaft 68 is two-point supported byboth the shaft support member 72 in an upper side thereof and the shaftsupport member 76 in a lower side thereof, so that the plunger 54 can bestably operated in the direction of axis line. An outer periphery of theshaft support member 76 is partially notched and thereby a communicatingpath is formed between the sleeve 52 and the shaft support member 76.The suction pressure Ps introduced into the solenoid 3 is filled througha communicating path between the core 50 and the shaft 68, acommunicating path between the plunger 54 and the sleeve 52, and acommunicating path between the shaft support member 76 and the sleeve52.

A spring 78 (functioning as a “second spring”) that biases the plunger54 in an upward direction, namely in a valve closing direction, is setbetween the shaft support member 76 and the plunger 54. In other words,as the spring load, the valve element 24 receives the net force of aforce exerted by the spring 40 in a valve opening direction and a forceexerted by the spring 78 in a valve closing direction. However, thespring load of the spring 40 is larger than that of the spring 78. Thus,the overall spring load of the springs 40 and 78 works in a valveopening direction. The spring load thereof can be set by adjusting thepress-fitting position of the shaft support member 76 in the sleeve 52.The press-fitting position thereof can be fine-adjusted such that abottom center of the sleeve 52 is deformed in the direction of axis lineby using a predetermined tool after the shaft support member 76 has beentemporarily press-fitted to the sleeve 52.

A pair of connection terminals 80 connected to the electromagnetic coil58 extend from the bobbin 56 and are led outside by passing through theend member 64. Note that only one of the pair of connection terminals 80is shown in FIG. 2 for convenience of explanation. The end member 64 ismounted in such a manner as to seal the entire structure inside thesolenoid 3 contained in the casing 60 from below. The ends of theconnection terminals 80 are led out from the end member 64 and connectedto a not-shown external power supply. The end member 64 also functionsas a connector portion through which the connection terminal 80 isexposed.

The control valve 1 configured as above is secured into a not-shownmounting hole formed in the compressor 101 via a washer. A plurality ofO-rings, which are set between the mounting holes and the control valve1 and which achieve the sealing capability, are fitted on an outerperipheral surface of the control valve 1. Annular grooves are formed onperipheries of the body 5 above and below the port 12, respectively, andO-rings 82 and 84 are fitted on the annular grooves. An annular grooveis also formed on a periphery of the connecting member 62 below the port14, and an O-ring 86 is fitted on the annular groove. Furthermore, anO-ring 88 is fitted on a connection area where the casing 60 and the endmember 64 are connected.

FIG. 3 is a partially enlarged cross-sectional view of the upper half ofFIG. 2. The diameter of a through-hole 90, which is formed in a centerof the valve seat forming member 16, is reduced in a lower half thereof.This reduced diameter portion of the through-hole 90 forms the valvehole 18. In other words, the upper half of the through-hole 90 is alarge-diameter part 92, whereas the lower half thereof is asmall-diameter part 94. And the small-diameter part 94 forms the valvehole 18. A connection area of the through-hole 90 in between thelarge-diameter part 92 and the small-diameter part 94 is a taperedsurface where the inside diameter thereof is gradually reduced downward.The diameter of the through-hole 90 is reduced in stages from anupstream side to a downstream side.

A bleed hole 96 in parallel with the through-hole 90 is formed inradially outward direction of the through-hole 90 in the valve seatforming member 16. The bleed hole 96 is used to ensure the circulationof oil in the compressor 101 by delivering a minimum requiredrefrigerant to the crankcase 116 even when the valve section is closed.The refrigerant contains a lubricating oil in order to ensure astabilized operation of the compressor 101, and the bleed hole 96 is toensure the oil circulation inside and outside the crankcase 116.

The bleed hole 96 is formed such that a leak passage 98 located in anupper part thereof and a communication passage 99 located in a lowerpart thereof are connected together. The inside diameter of the leakpassage 98 is of a size to a degree that the refrigerant is made to leaktherethrough, and the inside diameter thereof is fairly smaller thanthat of the valve hole 18. The inside diameter of the communicationpassage 99 is smaller than that of the large-diameter part 92 of thethrough-hole 90 and larger than that of the small-diameter part 94thereof. In a modification, the inside diameter of the communicationpassage 99 may be greater than or equal to that of the large-diameterpart 92 of the through-hole 90 or may be less than or equal to that ofthe small-diameter part 94 thereof.

A connection area of the leak passage 98 and the communication passage99 is a tapered surface where the inside diameter thereof is graduallyenlarged downward. The diameter of the bleed hole 96 is enlarged instages from an upstream side to a downstream side. An annular raisedportion 150 is formed on a top surface of the valve seat forming member16 in such a manner as to surround the through-hole 90, and the raisedportion 150 is of a stepped shape such that a radially inward portionand a radially outward portion of the valve seat forming member 16 arelower than the raised portion 150. The width of the raised portion 150is sufficiently small and is less than or equal to that of the valvehole 18 in the present embodiment. The leak passage 98 is opened upwardin a position of the raised portion 150. In other embodiments the widthof the raised portion 150 is smaller than the diameter of the largediameter part 92 of the through hole 90 shown in FIG. 3.

As described above, the bleed hole 96 is formed such that an inlet ofrefrigerant has a small diameter and the inlet thereof is opened on thetop surface of a stepped shape. Thus, the entry of foreign materialthrough the bleed hole 96 is prevented or suppressed. In other words, ifa foreign material, whose size is smaller than the mesh width of thestrainer 44, enters the port 10, it is highly improbable that theforeign material will enter through the bleed hole 96. This is becausethe width of the raised portion 150 is sufficiently small and the sizeof inlet of the bleed hole 96 is smaller. If the foreign material hitsthe raised portion 150, it is highly probable that the foreign materialis dropped to a lower position inside or outside the raised portion 150.In particular, even though the refrigerant flows through the bleed hole96 when the valve section is closed, the foreign material contained inthe refrigerant is unlikely to be led into the bleed hole 96. If theforeign material enters the port 10 when the valve section is opened,most of such foreign material will pass through the valve hole 18 and bedischarged from the port 12.

Also, in the valve chamber 20, the guide portion 30 protrudes in acentral part of the upper surface of the partition wall 26 and therebyan annular groove 152 is formed on the periphery of this protrusion (theguide portion 30). The outside diameter of the valve element 24 isslightly larger than that of the actuating rod 34 located immediatelybeneath the valve element 24. Thus, if the foreign material enters thevalve chamber 20 through the valve hole 18, it is highly improbable thatthe foreign material will enter a sliding portion of the actuating rod34 relative to the guiding passage 32. In the event that the foreignmaterial passes through the valve hole 18, most of such the foreignmaterial will be discharged through the port 12 or stay on in theannular groove 152 even though it should remain in the valve chamber 20.Thus, the remaining foreign material is less likely to enter a spacingor gap between the actuating rod 34 and the guiding passage 32. In otherwords, the annular groove 152 can function to trap the foreign materialtherein. Hence, this structure realized by the annular groove 152prevents the valve element 24 from being locked as a result of theentanglement of foreign material in the sliding portion of the actuatingrod 34 relative to the guiding passage 32.

In the present embodiment, the pressure sensitivity of the valve element24 is optimally set such that an effective pressure-receiving diameter a(the inside diameter of the valve hole 18) in the valve section of thevalve element 24 is slightly (e.g., by a very small amount) larger thana diameter b of the sliding portion of the actuating rod 34 (a>b). Inother words, such the setting as this increases the extent ofcontribution of the crank pressure Pc in a valve closing direction atthe time the valve section is opened, thereby making it slightlydifficult for the valve section to be opened. Thereby, the differentialpressure (Pd−Ps) slowly rises and the effect of the crank pressure Pc israised as compared with the case where a=b. As a result, the actuationresponsiveness of the wobble plate (cam plate) of the compressor 101 islowered so as to prevent or suppress the control hunting occurring whenthe valve section is opened. It is to be noted here that, for example,the technique disclosed in Japanese Patent Application Publication No.2006-57506 can be used to adjust the pressure sensitivity.

In the present embodiment, as described earlier, the guide portion 30protrudes as a larger protrusion on a working chamber 28 side than avalve chamber 20 side. Thereby, a lower end of the actuating rod 34 canprotrude from a lower end position of the body 5 (i.e., a lower endopening of the small-diameter part 42). This enables the retaining ring36 to be easily mounted to the actuating rod 34. In other words, inorder for the retaining ring 36 to be fitted to the actuating rod 34,the actuating rod 34 must first be inserted from the valve chamber 20side. This is because the outside diameter of the valve element 24 islarger than the size of the guiding passage 32. On the other hand, inorder for the retaining ring 36 to be fitted to the actuating rod 34, afitting part formed in the actuating rod 34 needs to be exposed from anopening end of the body 5 or at least the fitting part needs to bepositioned near the opening end thereof in consideration of theworkability. For this reason, if the guide portion 30 extends(protrudes) uniformly both above and below the partition wall 26, theactuating rod 34 needs to be unnecessarily made longer, which is notpreferable at all. In the light of this, in the present embodiment, theguide portion 30 is configured such that the guide portion 30 ispositioned in a lower part of the body 5. This configuration andarrangement ensure a more stabilized guiding function of the guideportion 30 and maintain an excellent workability when the retaining ring36 is to be mounted. Since the actuating rod 34 will not beunnecessarily long, the body 5 and eventually the control valve 1 aremade smaller-sized.

Furthermore, in the present embodiment as described above, the guideportion 30 and the spring 40 are each taper-shaped such that the outsidediameter thereof becomes gradually smaller downward. Thus, a lower halfof the spring 40 is contained in an upper end opening of the core 50,and the outside diameter of the small-diameter part 42 is made as smallas possible. Thereby, the outside diameter of the connecting member 62is made smaller, and an O-ring whose outside diameter is smaller can beselected as the O-ring 86. As a result, when the control valve 1 is tobe mounted through the mounting holes of the compressor 101, the effectof the refrigerant pressure acting in a direction opposite to a mountingdirection is reduced. That is, an area below the O-ring 86 has anatmospheric air pressure; if the size of the O-ring 86 is large, afixing structure having a high pressure withstanding property needs beimplemented in order to prevent the control valve 1 from fall off. Inthis regard, the O-ring 86 can be made small in the present embodimentand therefore it suffices that the control valve 1 has a simple fixingstructure such as a washer.

FIGS. 4A and 4B and FIGS. 5A and 5B are each a partially enlarged viewof the control valve 1. FIG. 4A is an enlarged view of a region Aencircled in FIG. 2, and FIG. 4B is an enlarged view of a region Bencircled in FIG. 2. FIG. 5A is a cross-sectional view taken along theline C-C and viewed on the arrows of FIG. 3. FIG. 5B is across-sectional view taken along the line D-D and viewed on the arrowsof FIG. 4B.

As illustrated in FIG. 4A, a surface of the core 50 is disposed counterto a surface of the plunger 54 and vice versa, and these facing surfacesof the core 50 and the plunger 54 are generally complementary in shapeto each other. Also, the outer circumferential edge of each facingsurface thereof is formed in a tapered shape. In other words, a lowerend surface of the core 50 has a flat surface 160 in a central partthereof and a tapered surface 162 in an outer circumferential edgethereof. The flat surface 160 is perpendicular to an axis line L1 of thecore 50, the inside diameter of the tapered surface 162 is largerdownward, and the tapered surface 162 forms an angle of θ1 relative tothe axis line L1. On the other hand, an upper end surface of the plunger54 has a flat surface 164 in a central part thereof and a taperedsurface 166 in an outer circumferential edge thereof. The flat surface164 is perpendicular to an axis line L2 of the plunger 54, the diameterof the tapered surface 166 is larger downward, and the tapered surface166 forms an angle of θ2 relative to the axis line L2. In the presentembodiment, θ1=θ2=45 degrees. The setting of the tapered surfacesadjusts the characteristics of the solenoid 3, and its detail will bediscussed later.

A recess 168 having a predetermined depth is formed in a center of theflat surface 164 of the plunger 54, and a retaining ring 70 is receivedby the recess 168. In other words, the interference between theretaining ring 70 and the core 50 is prevented.

As illustrated in FIG. 4B, a recess-like pressing force adjustment part170 is formed in a center of an underside of the reduced diameterportion 74 in the sleeve 52. A tip of a tool is placed in position andthen pressed on the pressing force adjustment part 170. Thereby, abottom face of the sleeve 52 is deformed in an upward direction of axisline (an inward direction of the sleeve 52) and the press-fittingposition of the shaft support member 76 is shifted while the bottom facethereof being deformed. This can fine-adjust the set load by the springs40 and 78.

In this manner, the shaft support member 76 is press-fitted to thesleeve 52, so that it can be maintained without varying the set loadthereof in the event that the bottom face of the sleeve 52 is deformedafter the set load thereof has been adjusted. In other words, in thepresent embodiment, as described above, carbon dioxide, which operatesin a high pressure, is used as the refrigerant and therefore even thesuction pressure Ps is high. Thus, there is a possibility that thebottom portion of the sleeve 52 deformed by the pressing forceadjustment part 170 will be deformed in a direction where the bottomportion thereof returns to the original position by the suction pressurePs. Should this happen, the shaft support member 76 will not be affectedby the deformation of the bottom portion thereof because the shaftsupport member 76 has been firmly secured to the inner wall of thesleeve 52. In other words, by employing the present embodiment, theconfiguration is such that the press-fitting position of the shaftsupport member 76 is regulated, so that the set load of the springs canbe stably maintained even in a high-pressure environment.

As illustrated in FIG. 4B, a space is formed between the end member 64and the sleeve 52. A communicating hole 172, which communicates betweenthe space and the exterior, is formed in a bottom portion of the endmember 64. The communicating hole 172 is an air hole through which torelease air in the space to the exterior when the sleeve 52 and the endmember 64 are assembled together, and functions as a passage throughwhich a pressure occurring in the space is to be released when they areto be assembled.

As illustrated in FIG. 5A, the shaft support member 72 is formed suchthat a so-called D-cut process is performed on the outer periphery of adisk-shaped body thereof. And a pair of flat surfaces 180 are formed. Acommunicating path 182 is formed between the flat surface 180 and aninner circumferential surface of the core 50. As illustrated in FIG. 5B,the shaft support member 76 is formed such that the so-called D-cutprocess is performed as well on the outer periphery of a disk-shapedbody thereof. And a pair of flat surfaces 184 are formed. Acommunicating path 186 is formed between the flat surface 184 and thesleeve 52. The suction pressure Ps of the working chamber 28 passesthrough the communicating paths 182 and 186 and is then filled withinthe sleeve 52.

In the above-described configuration, the diameter of the actuating rod34 is slightly smaller than the inside diameter of the valve hole 18 butis of a size approximately identical thereto. Thus, the effect of thecrank pressure Pc operating on the valve element 24 in the valve chamber20 is almost canceled out. As a result, the differential pressure(Pd−Ps) practically operates on the valve element 24 for apressure-receiving area having the approximately same size as that ofthe valve hole 18. The valve element 24 operates and moves such that thedifferential pressure (Pd−Ps) is kept at a preset differential pressureset by a control current supplied to the solenoid 3.

A basic operation of the control valve for the variable displacementcompressor is now explained.

In the control valve 1, when the solenoid 3 is turned off, the valveelement 24 gets separated away from the valve seat 22 by the net forceof the springs 40 and 78 in a valve opening direction with the resultthat the valve section is remained at a fully opened state. At thistime, a high-pressure refrigerant having the discharge pressure Pdintroduced into the port 10 from the discharge chamber 114 of thecompressor 101 passes through the fully-opened valve section and thenflows into the crankcase 116 through the port 12. As a result, the crankpressure Pc is raised and the compressor 101 carries out a minimumcapacity operation where the discharging capacity is the minimum.

When, on the other hand, at the startup of the automotive airconditioner or when the cooling load is the maximum, the value ofcurrent supplied to the solenoid 3 is the maximum and the plunger 54 isattracted by a maximum suction force of the core 50. At this time, theactuating rod 34 (including the valve element 24), the shaft 68 and theplunger 54 operate and move integrally altogether in a valve closingdirection, and the valve element 24 is seated on the valve seat 22. Thecrank pressure Pc drops by this valve closing movement and therefore thecompressor 101 carries out a maximum capacity operation where thedischarging capacity is the maximum.

When the value of current supplied to the solenoid 3 is set to apredetermined value while the capacity is being controlled, theactuating rod 34 (including the valve element 24), the shaft 68 and theplunger 54 operate and move integrally altogether. At this time, thevalve element 24 stops at a valve-lift position. This valve-liftposition is a position where five loads/forces are all balancedthereamong. Here, the five loads/forces are the spring load of thespring 40 that biases the actuating rod 34 in a valve opening direction,the spring load of the spring 78 that biases the plunger 54 in a valveopening direction, the load of the solenoid 3 that biases the plunger 54in a valve closing direction, the force by the discharge pressured Pdthat the valve element 24 receives in a valve opening direction, and theforce by the suction pressure Ps that the valve element 24 receives in avalve closing direction.

If, in this balanced state, the rotating speed of the compressor 101rises simultaneously with an increased engine speed and thereby thedischarging capacity increases, the differential pressure (Pd−Ps) willincrease and then the force in a valve opening direction will exert onthe valve element 24. As a result, the valve element 24 further upliftsits position and thereby the flow rate of refrigerant flowing from thedischarge chamber 114 to the crankcase 116 increases. This, in turn,causes the crank pressure Pc to rise and then the compressor 101operates in a direction such that the discharging capacity is reduced.Then the compressor 101 is controlled such that the differentialpressure (Pd−Ps) becomes the preset differential pressure. If the enginespeed drops, the compressor 101 operates in a manner reverse to theaforementioned operation and then the compressor 101 is controlled suchthat the differential pressure (Pd−Ps) becomes the preset differentialpressure.

FIG. 6 is a graph showing control characteristic of the solenoid 3. Thehorizontal axis of FIG. 6 indicates a value of current supplied to thesolenoid 3 (Isol (A)), and the vertical axis thereof indicates a presetdifferential pressure (Pd−Ps) (Mpa) as the control target value. In thepresent embodiment, the surface of the core 50, which faces the surfaceof the plunger 54, and the surface of the plunger 54, which faces thesurface of the core 50, are formed in the tapered shapes complementaryto each other, as described above. As a result, the resolution power ina high current domain is improved in a range of the control currentvalues (hereinafter referred to as a “control current value range”also).

In other words, as described above, the angles of the tapered surfacesat a core 50 side and a plunger 54 side are each set to 45 degrees(θ1=θ2=45 degrees in FIG. 4A). Thereby, as indicated by a solid line inFIG. 6, the characteristic after an intermediate value in the controlcurrent value range is varied. In other words, as the controlcharacteristic of the solenoid 3, the slope (rate of change or amount ofchange) of a preset differential pressure (Pd−Ps) relative to the valueof current supplied thereto (Isol) is set smaller in a high currentdomain after the intermediate value than the slope of a low currentvalue before the intermediate value. More specifically, the controlcurrent value range is the range of 0.2 A to 0.68 A, and the controlcharacteristic is varied before and after an intermediate value between0.2 A and 0.68 A, which is 0.45 A, as a boundary value. Thereby, theresolution power in the high current domain improves. This means thatwhen the preset differential pressure (Pd−Ps) is increased, a fineradjustment of the preset differential pressure can be made. In otherwords, the amount of change in the electromagnetic force of the solenoid3 can be made smaller in the high current domain than in the otherdomain. In the present embodiments, carbon dioxide, which operates undera high pressure, is used as the refrigerant. Thus, it is extremelyconvenient and advantageous that the accuracy of control can be enhancedin a range where the differential pressure is large.

A dashed line in FIG. 6 shows a case where the angle of the taperedsurface is set to 30 degrees (θ1=θ2=30 degrees), and a broken line showsa case where the angle of the tapered surface is set to 20 degrees(θ1=θ2=20 degrees). As evident from FIG. 6, the variation in thecharacteristic before and after the intermediate value (the boundaryvalue) can be made larger by taking a larger taper angle. Conversely,the variation in the characteristic before and after the intermediatevalue can be made smaller by taking a smaller taper angle. Hence, theoptimum control characteristic can be achieved by varying the taperangle in accordance with the specifications.

The description of the present invention given above is based uponillustrative embodiments. These embodiments are intended to beillustrative only and it will be obvious to those skilled in the artthat various modifications could be further developed within thetechnical idea underlying the present invention.

In the above-described embodiments, an example is shown where apress-fitting adjustment structure for adjusting the press-fitting ofthe shaft support member 76 to the sleeve 52 is applied to a so-called(Pd−Ps) differential pressure regulating valve. In a modification, thepress-fitting adjustment structure may be applied to a so-called (Pc−Ps)differential pressure regulating valve, for instance. In the (Pc−Ps)differential pressure regulating valve, a differential pressure (Pc−Ps)between the crank pressure Pc and the suction pressure Ps is broughtcloser to a preset differential pressure, which is a control targetvalue. In other words, the above-described press-fitting adjustmentstructure may be applied to a control valve that varies a dischargingcapacity of the compressor for compressing refrigerant led into thesuction chamber and discharges the compressed refrigerant from thedischarge chamber, by regulating the flow rate of refrigerant led out tothe suction chamber from the crankcase. Or alternatively, thepress-fitting adjustment structure may be applied to a so-called Pscontrol valve in which the suction pressure Ps is brought closer to apreset pressure, which is a control target value. In particular, whenthose control valves are to be applied to the supercriticalrefrigeration cycle that uses a refrigerant such as carbon dioxide, thefunctions of the above-described press-fitting adjustment structure areeffectively achieved.

In the above-described embodiments, an example is shown where the shaftsupport member 76 not only functions as a spring support for supportingthe spring 78 but also functions as a shaft support member forsupporting the shaft 68. In a modification, a spring support forsupporting the spring 78 and a shaft support member for supporting theshaft 68 may be provided separately; and the above-describedpress-fitting adjustment structure may be applied to this springsupport.

In the above-described embodiments, an example is shown where thecontrol valve having the above-described press-fitting adjustmentstructure is applied to the supercritical refrigeration cycle that usescarbon dioxide as the refrigerant. In a modification, a similar controlvalve may be applied to a supercritical refrigeration cycle that uses asubstance other than carbon dioxide as the refrigerant. Oralternatively, a similar control valve may be applied to a refrigerationcycle that does not operate in a supercritical range but to therefrigeration cycle where the pressure of refrigerant gets high.

In the above-described embodiments, an exemplary structure is shownwhere the actuating rod 34 and the shaft 68 are manufactured as separateunits and then they are coupled together such that one of them isabutted against the other thereof coaxially in the direction of axisline, thereby constituting the thus coupled one as a transmitting rodfor transmitting the solenoidal force to the valve element 24. In amodification, the actuating rod 34 and the shaft 68 may be integrallyformed as a single element.

In the above-described embodiments, a structure is shown where, in valveseat forming member 16, the inlet of refrigerant in the bleed hole 96has a small diameter and the inlet thereof is opened on the top surfaceof the stepped shape (see FIG. 3). This structure markedly achieves thefunction of suppressing the entry of foreign material in therefrigeration cycle where the refrigerant pressure gets high as in theabove-described embodiments. In other words, the higher the dischargepressure Pd is, the more it is likely that the foreign material entersthe port 10 by passing through the strainer 44. In spite of thisproblem, this function of suppressing the entry of foreign materialreduces at least the possibility that the foreign material will reach upto the valve chamber 20 through the bleed hole 96. This eventually leadsto maintaining the excellent control characteristic of the control valve1 in a high pressure environment.

In the above-described embodiments, an example is shown where the raisedportion 150 is formed annularly on the top surface of the valve seatforming member 16. It goes without saying that a shape other than thismay be employed. For example, the raised portion may be formed onlyaround the inlet of refrigerant of the bleed hole 96. Although, in theabove described-embodiments, an example is shown where only a singlebleed hole 96 is formed, a plurality of bleed holes 96 may be formed ina plurality of positions. In such a case, too, the inlet of refrigerantof each bleed hole 96 may preferably be provided on the top surface ofthe raised portion (stepped shape).

In the above-described embodiments, an example is shown where theannular groove 152 is formed such that an inward peripheral edge of thepartition wall 26 is lowered in height by one step (see FIG. 3). Thisstructure, too, markedly achieves the function of trapping the foreignmaterial in the refrigeration cycle where the refrigerant pressure getshigh as in the above-described embodiments. In other words, the higherthe discharge pressure Pd is, the more it is likely that the foreignmaterial enters the port 10 and eventually enters the valve chamber 20by passing through the strainer 44. In spite of this problem, thisfunction of trapping the foreign material reduces at least thepossibility that the foreign material will reach up to the gap betweenthe actuating rod 34 and the guiding passage 32. This eventually leadsto maintaining the excellent control characteristic of the control valve1 in a high pressure environment.

In the above-described embodiments, an example is shown where a singleannular groove is formed as a structure for trapping the foreignmaterial. Other structures than this may be employed, instead. Forexample, a plurality of annular grooves may be concentrically formed. Oralternatively, a small region on a center of the top surface of theguide portion 30 may have a raised portion and the guiding passage 32may be opened on the top surface of this raised portion. For example,the diameter of this raised portion may be less than or equal to ⅓ ofthe inside diameter of the valve chamber 20, and so forth; in thismanner, this raised portion may be sufficiently small-sized. Thediameter of this raised portion may be approximately equal to that ofthe valve element 24. In other words, this configuration may be suchthat an upper-end position of the guide portion 30 is higher than itssurrounding area, rather than the configuration where the groove isformed in the inward peripheral edge of the partition wall 26.

Though not mentioned in the above-described embodiments, thecommunicating hole 172 shown in FIG. 4B may be positioned directlybeneath the pressing force adjustment part 170, instead. In thismodification, the communicating hole 172 may also function as aninsertion hole for tools.

The present invention is not limited to the above-described embodimentsand modifications only, and those components may be further modified toarrive at various other embodiments without departing from the scope ofthe invention. Also, various other embodiments may be further formed bycombining, as appropriate, a plurality of structural componentsdisclosed in the above-described embodiments and modification. Also, oneor some of all of the components exemplified in the above-describedembodiments and modifications may be left unused or removed.

What is claimed is:
 1. A control valve for a variable displacementcompressor for varying a discharging capacity of the compressor forcompressing refrigerant led into a suction chamber and discharging thecompressed refrigerant from a discharge chamber, by regulating a flowrate of the refrigerant led into a crankcase from the discharge chamber,the control valve comprising: a body having a discharge chambercommunication port communicating with the discharge chamber, a crankcasecommunication port communicating with the crankcase, a valve hole formedin a passage connecting the discharge chamber communication port and thecrankcase communication port, and a valve chamber formed between thevalve hole and the crankcase communication port; a valve element foropening and closing a valve section by moving toward and away from thevalve hole, the valve element being arranged in the valve chamber; asolenoid, provided on the body, which generates a solenoidal force withwhich to drive the valve element in a valve closing direction inaccordance with an amount of current supplied thereto; and a bleed holethat enables the refrigerant to be leaked from the discharge chambercommunication port to the valve chamber while the valve section is beingclosed, the bleed hole having a leak passage, whose diameter is smallerthan that of the valve hole, and the bleed hole being provided radiallyoutward of the valve hole in the body, wherein the valve holeconstitutes part of a through-hole extending in a direction of axis linethrough a member for separating the discharge chamber communication portfrom the valve chamber inside the body, wherein the through-hole and thebleed hole are formed through the member in such a manner that each ofthe through-hole and the bleed hole allows the discharge chambercommunication port and the valve chamber to communicate with each other,wherein the member has a flat surface with an opening at which thethrough-hole is open toward the discharge chamber communication port,and a raised portion protruding from the flat surface toward thedischarge chamber communication port, wherein the through-hole has alarge-diameter part being open on the discharge chamber communicationport side, and a small-diameter part, the small diameter part definingthe passage that forms the valve hole and being open on a valve chamberside and having a diameter smaller than a diameter of the large-diameterpart, wherein the raised portion has a width smaller than the diameterof the large-diameter part, and wherein the leak passage is open on thedischarge chamber communication port side at a top surface of the raisedportion.
 2. The control valve, for a variable displacement compressor,according to claim 1, wherein control is performed such that adifferential pressure between a discharge pressure of the dischargechamber and a suction pressure of the suction chamber is maintained at apreset differential pressure according to a value of current supplied tothe solenoid.
 3. The control valve, for a variable displacementcompressor, according to claim 1, wherein the control valve is appliedto a refrigeration cycle in which a refrigeration operation is performedin a supercritical range exceeding a critical temperature of therefrigerant.
 4. The control valve, for a variable displacementcompressor, according to claim 3, wherein control is performed such thata differential pressure between a discharge pressure of the dischargechamber and a suction pressure of the suction chamber is maintained at apreset differential pressure according to a value of current supplied tothe solenoid.
 5. The control valve, for a variable displacementcompressor, according to claim 1, wherein the body includes a suctionchamber communication port communicating with the suction chamber, aworking chamber, which allows the suction chamber communication port andan interior of the solenoid to communicate with each other, a partitionwall, which divides an internal space of the body into the valve chamberand the working chamber, and a guiding passage formed in the partitionwall, the control valve further comprising an actuating rod thattransmits the solenoidal force to the valve element, wherein theactuating rod is slidably supported by the guiding passage, and one endof the actuating rod is coupled to the valve element in the valvechamber and the other end thereof is coupled to the solenoid, wherein aguide portion, which so protrudes as to form a step, is provided on anend surface of the partition wall at a valve chamber side, and whereinthe guiding passage is open on the valve chamber side in the guideportion.
 6. The control valve, for a variable displacement compressor,according to claim 5, wherein control is performed such that adifferential pressure between a discharge pressure of the dischargechamber and a suction pressure of the suction chamber is maintained at apreset differential pressure according to a value of current supplied tothe solenoid.
 7. The control valve, for a variable displacementcompressor, according to claim 5, wherein the control valve is appliedto a refrigeration cycle in which a refrigeration operation is performedin a supercritical range exceeding a critical temperature of therefrigerant.
 8. The control valve, for a variable displacementcompressor, according to claim 7, wherein control is performed such thata differential pressure between a discharge pressure of the dischargechamber and a suction pressure of the suction chamber is maintained at apreset differential pressure according to a value of current supplied tothe solenoid.
 9. The control valve, for a variable displacementcompressor, according to claim 1, wherein the bleed hole is formed suchthat the leak passage and a communication passage, whose diameter islarger than that of the leak passage, are connected in the direction ofaxis line, and wherein the communication passage is open on the valvechamber side.
 10. The control valve, for a variable displacementcompressor, according to claim 9, wherein control is performed such thata differential pressure between a discharge pressure of the dischargechamber and a suction pressure of the suction chamber is maintained at apreset differential pressure according to a value of current supplied tothe solenoid.
 11. The control valve, for a variable displacementcompressor, according to claim 9, wherein the control valve is appliedto a refrigeration cycle in which a refrigeration operation is performedin a supercritical range exceeding a critical temperature of therefrigerant.
 12. The control valve, for a variable displacementcompressor, according to claim 11, wherein control is performed suchthat a differential pressure between a discharge pressure of thedischarge chamber and a suction pressure of the suction chamber ismaintained at a preset differential pressure according to a value ofcurrent supplied to the solenoid.
 13. The control valve, for a variabledisplacement compressor, according to claim 9, wherein the body includesa suction chamber communication port communicating with the suctionchamber, a working chamber, which allows the suction chambercommunication port and an interior of the solenoid to communicate witheach other, a partition wall, which divides an internal space of thebody into the valve chamber and the working chamber, and a guidingpassage formed in the partition wall, the control valve furthercomprising an actuating rod that transmits the solenoidal force to thevalve element, wherein the actuating rod is slidably supported by theguiding passage, and one end of the actuating rod is coupled to thevalve element in the valve chamber and the other end thereof is coupledto the solenoid, wherein a guide portion, which so protrudes as to forma step, is provided on an end surface of the partition wall at a valvechamber side, and wherein the guiding passage is open on the valvechamber side in the guide portion.
 14. The control valve, for a variabledisplacement compressor, according to claim 13, wherein control isperformed such that a differential pressure between a discharge pressureof the discharge chamber and a suction pressure of the suction chamberis maintained at a preset differential pressure according to a value ofcurrent supplied to the solenoid.
 15. The control valve, for a variabledisplacement compressor, according to claim 13, wherein the controlvalve is applied to a refrigeration cycle in which a refrigerationoperation is performed in a supercritical range exceeding a criticaltemperature of the refrigerant.
 16. The control valve, for a variabledisplacement compressor, according to claim 15, wherein control isperformed such that a differential pressure between a discharge pressureof the discharge chamber and a suction pressure of the suction chamberis maintained at a preset differential pressure according to a value ofcurrent supplied to the solenoid.